Pallet with composite components

ABSTRACT

A pallet having a first deck,a second deck, and a plurality of composite block members securing the first and second decks together to form a pallet. The composite block members and lead boards of the first and/or second deck comprise a composite material including about 50%-55% by weight of juniper or conifer particles and about 45%-50% by weight of a plastic component including a major portion of polyethylene.

FIELD OF THE INVENTION

The present invention relates to a pallet, and more particularly, apallet having composite components.

BACKGROUND OF THE INVENTION

The common wooden and plastic industrial pallets are generally known inthe art. Such pallets, however, have several shortcomings in regards tocost, quality, limitations of their use, and ease of manufacture. Woodenpallets are typically constructed by sandwiching wooden block membersbetween two similar decks or surfaces. Since the aesthetic appearance ofpallets may not outweigh the cost, they may often include scrap orrecycled wood. The surfaces may be made of a continuous sheet or, morecommonly, have a plurality of wooden boards typically arranged in aparallel manner. Generally, the surfaces and blocks are stacked orarranged to provide apertures suitable for access by the tines of aforklift truck or pallet jack from at least one side. In certaininstances, the tines of a fork-lift truck make contact with the blockmembers during alignment. If the force is significant, the block memberscan be damaged.

By its nature, ordinary wood may be subject to swelling, warping,shrinkage, splintering, deterioration and fungal or bacterial growthafter exposure to moisture and other elements. Pallets assembled withinferior quality wood blocks and/or boards may lead to potential cargodamage.

Attempts to overcome the drawbacks of ordinary wooden pallets withplastic pallets have been faced with similar shortcomings. Prior designsof plastic pallets have had to deal with issues such as the trade offbetween cost and weight bearing capability. Typically, plastic palletsdesigned with a significant weight bearing capability have tended to beboth heavy and expensive. In the same manner, inexpensive plasticpallets have had both strength and durability issues.

It is therefore desirable to provide a long-life pallet with outstandingphysical attributes that is relatively inexpensive and can bemanufactured with relative ease. Specifically, it is desirable toprovide a low cost pallet that meets and exceeds stringent strengthstandards, including the needs and requirements of the GroceryManufacturers Association (GMA).

SUMMARY OF THE INVENTION

The present invention provides a pallet having an upper deck and a lowerdeck. Composite block members connect the upper and lower decks togetherto form a pallet. Preferably, the block members are formed of acomposite material including at least about 20% by weight of a naturalmaterial and at least about 20% by weight of a plastic material. Invarious embodiments, the composite material includes from about 50% toabout 55% by weight of natural material particles having an averageparticle size of less than about 0.25 inches, and from about 45% toabout 50% by weight of plastic material particles comprising a majorportion of polyethylene. The natural material particles of the presentinvention include ground particles of whole trees selected from thegroup consisting of junipers and conifers. The whole trees include rootparticles, trunk particles, branch particles, needle particles, woodparticles, and mixtures thereof.

The present invention also relates to a pallet including an upper deckhaving a plurality of cross members, and a lower deck having a pluralityof cross members. The decks are joined with block members forming apallet. The upper and lower decks have a substantially rectangular frameand include a plurality of longitudinally and laterally extending crossmembers. At least one of the plurality of cross members is a compositematerial comprising at least about 20% by weight of natural materialparticles ground from whole trees and at least about 20% by weight ofplastic material particles. Preferably, the pallet has at least onecomposite material lead board.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a pallet in accordance with theteachings of the present invention;

FIG. 2 is an exploded perspective view of a pallet according to thepresent invention and showing the individual components thereof;

FIG. 3 is a perspective view of a composite block member;

FIG. 4 is a top view of the composite block member of FIG. 3; and

FIG. 5 is a side view of the composite block member of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For purposes of clarity, the same referencenumbers will be used in the drawings to identify similar elements.

In various embodiments, the present invention provides a palletincluding a first deck, a second deck and a plurality of block membersconnecting the first and second decks together. The block members, andoptionally certain boards or cross members of the decks, comprise a highstrength composite material. The composite material has excellentresistance to chemicals, including strong solvents, and is not moistureor odor absorbent. Such composite blocks and boards are robust andrugged in construction, configured to withstand the weight of goodsstacked on them and to withstand the impact of truck forks driven intothem as a result of misalignment. A pallet comprising such compositematerial also has the capability of being fitted with RFID technology.

The composite material of the present invention includes a naturalmaterial, such as wood, and a plastic material. As used herein, “naturalmaterial” includes wood, for example, material from a tree, includingbut not limited to leaf material, branch material, trunk material, barkmaterial, needle material, and root material. As used herein, the term“wood” includes, but is not limited to, juniper and conifer trees andother hard and soft wood trees, such as Apache Plume; Ash, single-leaf;Bitterbrush; Cliffrose; Fendlerbush; Juniper, one-seed; Juniper, rockymountain; Mahogany, curl-leaf; Mahogany, mountain; Mock Orange;Ponderosa Pine; Mormon Tea; and various other cone-bearing gymnospermoustrees, spruces, firs, pines, shrubs, and evergreens. Further, as usedherein, “plastic material” includes, but is not limited to, variousplastic materials, such as thermoplastic polymers resistant to manychemical solvents, bases and acids, for example, polypropylene,polyethylene, polyurethane, polyvinylchloride, and poly(ethyleneterephthalate). The plastic material may also include various types andgrades of nylon. The plastic may be selected depending on the specificpallet design, load capacity, and other requirements. The plastic caninclude virgin plastic, recycled plastic, and mixtures thereof.

In various embodiments, the composite material of the present inventioncomprises at least 20% by weight natural material particles and at least20% by weight plastic material particles. In one embodiment, thecomposite material comprises about 70% by weight natural particles andabout 30% by weight plastic materials. According to other preferredembodiments, the composite material comprises greater than about 40% byweight natural material particles, and preferably greater than about50%, such as between about 50% to about 55% by weight. Preferably, thecomposite material comprises greater than about 35% by weight plasticmaterials, and preferably greater than about 45% by weight of plasticmaterial particles, such as between about 45% to about 50% by weight. Itshould be understood that the weight percentages can be increased ordecreased for a desired composite material, depending on the specificdesign and selection of materials, and these variations are within thescope of the present invention.

Optional additives for the composite material include colorants, UVprotectors, flame and fire retardants, lubricants, soaps, various inertfillers, reinforcements (including, for example, natural, synthetic, andglass fibers), polymerization initiators, coupling agents, and otheradditives known in the art. Additionally, the composite material isrecyclable to itself as filler. In particular, the use of couplingagents in the composite matrix may improve thickness swell and increasethe resistance to UV exposure and surface popping. Coupling agentsincrease the bond between the natural and plastic materials whichtypically increases the stiffness and strength by up to about 30%.Alternatively, if it is not desirable to use a coupling agent, theaverage particle size can be slightly decreased to maintain anequivalent strength.

The wood particles used in the present invention are preferablyelongated shapes having a width or average particle size that is about ¼(0.25) inch or less. In various embodiments, the width is 1/16 (0.0625)inch or less, and even more preferably, 1/32 (0.03125) inch or less. Itshould be understood that the average particle size can be increased ordecreased, depending on the specific design and selection of materials,and these variations are within the scope of the present invention. Itshould further be noted that the average particle size is not based onthe total number of particles but rather is based on the weightpercentage of the material retained in measuring sieve trays in relationto the total sieved material weight. Natural material particles oftenhave unequal dimensions, for example a length greater than a width. Insuch circumstances, a particle size refers to at least one dimensionhaving the specified size. Particle size distribution can be determinedusing Gaussian distribution, or other methods known in the art.

In certain embodiments, and preferably where the composite material isused to manufacture sheet boards that are subsequently cut into leadboards, it may be desirable to use a larger wood particle size andinclude the use of reinforcing wood fibers. Such wood fibers can be usedhaving an average length of about ⅜ inch, ½ inch, ¾ inch, or evengreater as desired.

The wood particles can be processed in a hammermill using a desiredscreen size. This enables distribution of the wood material product in asubstantially even manner for use in the composite material. In variousembodiments, the particles have a random orientation in the finalproduct, although with some embodiments using extrusion techniques itmay be desired to have a process-specific orientation. Further, ifreinforcing fibers are used, it may be desired to align the fibers forincreased strength.

The manufacture of the composite material of the present invention intovarious geometries is preferably achieved using press methods and/orextrusion techniques known in the art. Typically, the wood or naturalmaterials are first passed through a mill to obtain a desired particlesize. The plastic materials are provided in a form suitable for mixingwith the natural materials, for example, in the form of a fluid, pellet,flake, powder, or the like. As will be discussed in more detail, in oneembodiment, the composite material is manufactured having a board orpanel geometry suitable for use as cross members and/or lead boardmembers for the upper and/or lower deck of the pallet. In anotherpreferred embodiment, the composite material is manufactured having ablock or post geometry for use as supporting blocks that join the upperand lower decks to one another.

Press methods rely on at least one press and include suitable pneumatic,mechanical and/or hydraulic presses that process wood/plastic mixturesinto, for example, a block or a composite board. As known in the art,the press typically includes an upper platen and a lower platen. Atleast one platen is driven upward or downward by a drive mechanism. Acomposite material assembly is positioned between the upper and thelower platens. A typical composite material press assembly may include alower caul plate, a frame, the composite mixture and an upper caulplate. According to one embodiment of the present invention, at leastone of the platens is heated to a temperature sufficient to melt theplastic component of the composite material. Heating of the platen(s)occurs optionally before or after engagement of the drive mechanism. Inone embodiment, both platens are heated prior to application of pressureto the composite mixture. Preferably, the drive mechanism drives thelower platen upwards until the upper platen contacts the upper caulplate and compresses the composite mixture.

The plastic component of the composite material mixture melts from theheat and disperses throughout the discontinuous wood phase. Thecomposite material essentially forms a slurry of liquid plastic and woodparticles. Preferably, air (and any other gas that may be present) exitsthe composite mixture during this process or it is alternativelycompressed and trapped within the slurry. The slurry is typically of adensity greater than that of the composite mixture and occupies a lesservolume than the mixture. The slurry is then cooled and forms arelatively rigid composite product, such as a board. Rigidity andstrength of the final product will depend upon the thickness, the typeof plastic used, the ratio of natural and plastic materials, the amountand pressure of any entrained gas, and whether a reinforcing material,such as rods, bars, or a mesh, is incorporated into the slurry. Itshould be understood that caution is required when positioning thematerials into the press to avoid segregation of the wood and plasticmaterials. Minimized segregation often forms a higher quality compositeboard.

Preparation of the natural material, such as wood, typically includesthe main steps of: logging, grinding, screening, washing, and drying.Logged whole trees are ground to particles having a maximum dimension ofabout 12 inches. The wood particles are then placed in a grinder, suchas a hog grinder, and ground having a maximum dimension from about 3 toabout 5 inches. The ground wood is screened, washed, and dried to removedebris, such as dirt and sand. Preferably, the drying step reducesmoisture content of the ground, screened and/or washed wood to amoisture content of less than about 15% by weight, preferably to amoisture content of less than about 10% by weight, and even morepreferably to a moisture content of less than about 5% by weight. Next,the wood is ground to a maximum particle size less than about 0.5inches, preferably to a particle size less than about 0.25 inches, morepreferably to a particle size less than about 0.0625 inches, and evenmore preferably to a particle size less than about 0.03125 inches.Larger wood fibers can also be added for additional reinforcement.

Washing conditions and screening conditions should be selected tofacilitate further processing and to enhance the quality of the finalproduct. For example, additives known to affect wood are optionallyadded to the washing solution. Such non-limiting additives includeacids, bases, enzymes (e.g., cellulosic enzymes), gas concentrations,and the like. Environmental conditions of the washing solution, such astemperature and pressure, are also adjustable to promote overallefficiency. It should be understood that the effect of additives andenvironmental conditions can be cumulative and/or synergistic, andoperate through physical and/or chemical principles. Washing optionallyincludes washing with a gas, such as delivering gas at a pressuresufficient to remove debris.

In certain embodiments, flaking of washed and/or screened chips isperformed in a processing facility. One purpose of flaking is to reducethe size of tree chips to a desired size. In one preferred embodiment,tree chips are flaked to a size of less than approximately 2 inches, andmore preferably to less than approximately 0.5 inches. Flaked tree chipsare herein referred to as flakes.

In one preferred embodiment, the wood preparation methods and pressand/or extrusion methods can be combined into one production process.For example, a wood receiver can be used for receiving wood that istransported to a screen for screening out undesirable larger pieces ofwood. Once screened, the wood is transported to a reducer for reducingthe size of the screened wood. The reduced wood is transported to awasher and/or screener that can optionally include a re-chipper forfurther reduction of the screened wood particle size. Next, the washedwood is flaked using an appropriate flaker and transported to a flakereceiver that optionally includes a heater and/or dryer and/or a dustburner. Flakes are then transported to a grinder for grinding and/orsizing of the wood. The ground wood is then transported to a sifter forsifting fines from larger pieces of wood. Fines are transported to andstored in a fines receiver while the larger pieces are transported toand stored in a processed wood receiver. The fines receiver andprocessed wood receiver can optionally use filters. The processed woodand/or fines are then ready for further processing and/or combinationwith plastic.

Plastic materials typically enter the production process through aplastic receiver. The plastic in a plastic loader is optionallytransported to a plastic storage receiver for storage and/or furtherprocessing. The plastic storage receiver optionally includes a filter.Once the plastic has been processed and/or stored, it is thentransported to a measurement system, for example, a weigh station systemand/or flow measurement system. The plastic and wood are transported toa blender for blending plastic and wood. Blended plastic and wood aretransported to a production line that includes a press and/or anextruder. The production line produces a final product or optionally hasadditional equipment for performing additional steps for producing thefinal product. For example, the production line can optionally includean unloader and/or cooler; at least one trimmer and/or borer; at leastone transfer and/or inspection unit; a sander; a paint unit, forexample, for spray painting (if desired); an oven, for example, forcuring paint and/or other coating material; a grade station; and/or astacker, for stacking product.

One presently preferred extruded composite material includes a lowdensity polyethylene (LDPE) film mixed with conifer or juniper material.The composite material includes approximately 45% to about 50% by weightLDPE film and approximately 50% to about 55% by weight conifer orjuniper. Preferably, the conifer or juniper material particles have anaverage particle size less than about 0.0625 inches. In certainembodiments, wood fibers are included having an average length of fromabout ⅜ to about ¾ inches. The LDPE film is preferably a nominal ¼ inchgrind according to a sieve analysis conducted on the plastic material todetermine the particle size distribution and approximate averageparticle size. A 50% by weight plastic level is preferred to make asuperior exterior board substrate. In various embodiments, the compositematerial has a density of 50 pcf, and an average water absorption ofless than about 15% by weight.

As shown in FIG. 1 and generally referenced by the number 10, the palletof the present invention has four peripheral sides 12, or edges,defining the perimeter. Preferably each side 12 is disposed at asubstantially right angle, thereby forming a rectangular shape. In onepreferred embodiment, the pallet is constructed having the industrystandard size and dimensions, which is currently 40 inches wide by 48inches long (1.0 m by 1.2 m), although it may be made in any desiredsize or shape. The pallet 10 includes an upper deck 14 and a lower deck16, each preferably being formed of a plurality of longitudinally andlaterally extending cross members 18 and lead boards 19. As shown, thelead boards 19 may be the same size as the remaining cross members 18,or slightly larger to provide suitable additional strength. Preferably,they have dimensions of about 5½ inches wide, 40 inches long and 11/16inches thick. Once assembled, the upper and lower decks 14, 16 are heldtogether with a plurality of separating members, or blocks, generallyreferenced by the number 20.

As previously mentioned, at least one of the block members 20, andoptionally certain cross members 18 of the decks, such as the leadboards 19, comprise the high strength composite material of theinvention. For example, in certain embodiments, the block members 20comprise the composite material, and the cross members 18 are standardwooden pieces. In other embodiments, the block members 20 and leadboards 19 comprise the composite material. In still other embodiments,each member of the pallet 10 can comprise the composite material. Itshould be understood that numerous combinations and designsincorporating composite material blocks 20 and composite board crossmembers 18 and lead boards 19 are possible, and all of the variationsare within the scope of the invention.

FIG. 2 depicts an exploded perspective view of the pallet 10 of FIG. 1,showing the individual components spaced apart from one another, andwhich comprise the upper deck 14, the lower deck 16, the cross members18, and the plurality of blocks 20. Each block 20 holds the upper andlower decks 14, 16 together, while bearing and distributing the cargoloads placed on the upper deck 14. In preferred embodiments, the blocks20 are mechanically fastened to the upper and lower decks, for example,with nails or screws. Preferably, there are nine blocks 20, aligned inthree rows of three, defining two apertures 22 on each side 12 of thepallet 10. Ideally, each pallet has four corner blocks 24, four mid-sideblocks 26, and one center block 28. The size of the apertures 22 willdepend upon the size and length of the blocks 20.

Preferably, the blocks 20 are of a sufficient size so that the apertures22 define a space suitable for access by the tines, or forks, of aforklift truck or pallet jack from any of the four sides 12 of thepallet 20. The current industry standard is to have apertures 22 with aseparation distance D of about 3.5 inches between the upper deck 14 andlower deck 16. Thus in one embodiment as shown in FIGS. 3-5, the blockshave a height H of about 3.5 inches, a width W of about 3.65 inches, anda length L of about 4.75 inches.

For additional impact resistance, the blocks 20 are preferably providedwith curved ends, thereby minimizing potential damage which may occurupon collision or brunt contact. As shown, the blocks 20 have anelongated elliptical shape, including a planar top surface 30, a planarbottom surface 32, and two substantially circular side sections 34sandwiching a substantially flat section 36. It should be understoodthat the specific size and shape of the composite block members can bemodified as necessary and desired, and variations of the overall sizeand shape are within the scope of the present invention.

In various embodiments, the upper deck 14 defines a generally planarload bearing surface upon which objects and goods may be positioned fortransport and storage. The lower deck 16 defines a substantially planarbottom surface for the secure placement of the pallet on the ground orother resting surface. This also allows for the stable stacking of thepallet onto a similarly designed pallet. In certain embodiments, theupper and/or lower decks 14, 16 can comprise a continuous sheet ofmaterial (not shown). In these embodiments, a number of indentations andprojections such as ridges and channels (not shown) may be formed in thetop of the upper deck to allow for the drainage of any liquids that mayaccumulate thereon. Alternate embodiments may include further channelsconfigured to direct fluid to the sides of the pallet if necessary. Itshould be noted, however, that the number, orientation, size and shapeof any ridges or channels can be varied in many alternate configurationsfor optimized strength. Of course, the upper or lower deck 14, 16 mayalso have a continuous surface without apertures if so desired.

The load bearing surface may have a texture or an etched or imprintedgeometrical pattern thereon (not shown) that acts as a non-skid surfaceto prevent objects from sliding during transport. Alternatively, anysuitable type of friction tape, or friction coating may be applied orlaminated to the load bearing surface in order to help prevent movementof objects on the pallet.

Preferably, the lower deck 16 includes longitudinally and laterallyextending cross-members aligned and connected to form a substantiallyrectangular shaped outer frame. As shown, one arrangement of thecross-members includes two relatively large apertures 38 allowing airflow through the pallet and also for accommodating pallet jacks. Whileshown as substantially rectangular in shape, the apertures 38 may besized and shaped for other desired applications. Additionalcross-members may be used, depending upon the desired load capacity ofthe pallet 10. In alternate embodiments, the size and number ofapertures 38 will depend upon the placement and number of cross-membersused.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A pallet comprising: a first deck; a second deck; and a plurality of block members connecting the first and second decks together to form a pallet, the block members comprising a composite material including at least about 20% by weight of natural material particles and at least about 20% by weight of plastic material particles.
 2. The pallet according to claim 1, wherein the natural material particles comprise ground particles of whole trees selected from the group consisting of junipers and conifers, the whole trees including root particles, trunk particles, branch particles, needle particles, wood particles, and mixtures thereof.
 3. The pallet according to claim 2, wherein the natural material particles comprise at least one wood selected from the group consisting of: Apache Plume; Ash, single-leaf; Bitterbrush; Cliffrose; Fendlerbush; Juniper, one-seed; Juniper, rocky mountain; Mahogany, curl-leaf; Mahogany, mountain; Mock Orange; Ponderosa Pine; Mormon Tea; and mixtures thereof.
 4. The pallet according to claim 1, wherein the plastic material particles comprise at least one material selected from the group consisting of polypropylene, polyethylene, polyurethane, polyvinylchloride, poly(ethylene terephthalate), nylon, and mixtures thereof.
 5. The pallet according to claim 1, wherein at least one of the first and second decks comprises a substantially rectangular frame having a plurality of longitudinally and laterally extending cross members, further wherein at least one of the plurality of cross members comprises a composite material comprising at least about 20% by weight of natural material particles ground from whole trees and at least about 20% by weight of plastic material particles.
 6. The pallet according to claim 5, wherein the at least one cross member comprises a lead board.
 7. The pallet according to claim 1, wherein the block members comprise at least about 50% by weight of natural material particles.
 8. The pallet according to claim 1, wherein the block members comprise at least about 45% by weight of plastic material particles.
 9. The pallet according to claim 8, wherein the block members comprise at least about 45% by weight of a thermoplastic component comprising a major portion of polyethylene.
 10. The pallet according to claim 1, wherein the block members further comprise at least one filler selected from the group consisting of colorants, UV protectors, flame and fire retardants, lubricants, soaps, polymer initiators, coupling agents, and mixtures thereof.
 11. The pallet according to claim 1, wherein the block members have an average water absorption of less than about 15% by weight.
 12. The pallet according to claim 1, wherein the block members are press-formed.
 13. The pallet according to claim 1, wherein the block members are formed using extrusion techniques.
 14. The pallet according to claim 1, wherein the natural material particles have an average particle size of less than about 0.25 inches and have a random orientation in the composite material.
 15. The pallet according to claim 14, wherein the natural material particles have an average particle size of less than about 0.0625 inches.
 16. A pallet comprising: a first deck comprising a first plurality of cross members; a second deck comprising a second plurality of cross members; and a plurality of block members connecting the first and second decks together to form a pallet, wherein at least one block member and at least one cross member of the first or second plurality of cross members comprise a composite material including at least about 50% by weight of a natural material and at least about 45% by weight of a plastic material comprising a major portion of polyethylene.
 17. The pallet according to claim 16, wherein the at least one cross member comprises a lead board.
 18. The pallet according to claim 16, wherein the at least one cross member comprises a composite material including wood fibers having an average length of from about ⅜ to about ¾ inches.
 19. The pallet according to claim 16, wherein the plastic material comprises at least one material selected from the group consisting of polypropylene, polyethylene, polyurethane, polyvinylchloride, poly(ethylene terephthalate), nylon, and mixtures thereof.
 20. The pallet according to claim 16, wherein the block members further comprise at least one filler selected from the group consisting of colorants, UV protectors, flame and fire retardants, lubricants, soaps, polymer initiators, coupling agents, and mixtures thereof.
 21. A pallet comprising: a first deck comprising a first plurality of cross members; a second deck comprising a second plurality of cross members; and a plurality of extruded, elliptical shaped composite block members connecting the first and second decks together to form a pallet, wherein the block members and at least one cross member of the first or second plurality of cross members comprise a composite material including from about 50% to about 55% by weight of natural material particles having an average particles size of less than about 0.25 inches, and from about 45% to about 50% by weight of plastic material particles comprising a major portion of recycled, low density polyethylene.
 22. A method of making a pallet comprising: preparing and blending a mixture comprising from about 50% to about 55% by weight of natural material particles and from about 45% to about 50% by weight of plastic material particles; heating and extruding the mixture forming a composite material of a desired shape; cutting the composite material into blocks; and securing the blocks to substantially rectangular shaped upper and lower decks to form a pallet. 